Optical clarity.
UV stable.
Polishable.

Acrylic: better optical clarity (93% vs 88%), scratch resistant, UV stable, cheaper, brittle. Polycarbonate: 250× impact resistance, slightly lower clarity, softer surface (scratches easily), more expensive. For displays and decorative: acrylic. For safety (bulletproof, impact): polycarbonate. For outdoor long-term: acrylic. For high-abuse: polycarbonate.

Yes via diamond polishing or vapor polishing after CNC. Typical sequence: CNC machine to near-final dimension, fine sand progressively (400, 600, 1200, 2500 grit), diamond polish or vapor polish. Final finish Ra 0.05 µm — truly optical. For less-critical applications, flame polishing edges alone gives visually acceptable result at much lower cost.

Acrylic crazes (fine network of cracks) when exposed to certain chemicals under stress. Common offenders: solvents, some cleaners, aromatic hydrocarbons, specific adhesives. Cast acrylic is more resistant than extruded. Design considerations: avoid concentrated stress risers, test cleaning chemicals before use, use polycarbonate if stress-crack-prone chemistry is expected.

Yes for cast acrylic. UV-grade cast PMMA maintains 85% of original clarity after 10-20 years outdoor exposure. Better than most plastics. Extruded acrylic has shorter outdoor service life (5-10 years typical). For long-life outdoor applications (signage, architectural), specify cast acrylic with UV-stabilized formulation.

Sharp tools essential (dull tools cause melting). Slow feeds initially to prevent cracking. Avoid flood coolant — can cause stress cracks. Air blast or mist coolant preferred. Climb milling over conventional. For cast acrylic, standard CNC tolerances (±0.05 mm) easy. Extruded acrylic: plan for 0.1-0.3% dimensional change from stress relief after machining.

Standard cast acrylic sheet: in stock 1-3 day lead time. Custom thickness: 7-10 days. Colored cast: 5-10 days. Custom tint colors: 3-4 weeks. With polishing: add 3-5 days. Specialty grades (museum UV, anti-static): 2-3 weeks.